A power supply device, a distributed power storage device, and an electric vehicle, using an assembled battery having a plurality of secondary cells have a battery management device that optimally manages the secondary cells mounted thereon. As a state of the secondary cells that are managed by the battery management device, a state of charge (state of charge: SOC) indicating how much the secondary cell is charged, or how much a dischargeable charge amount remains is a typical example.
In the power supply device using a plurality of secondary cells connected in series, an SOC equalizing function is implemented for the purpose of maintaining an SOC dispersion attributable to an individual variability of self-discharge of the secondary cells within a given range. Also, there is an individual variability in an internal resistance and a full charging capacity of the secondary cells, and the internal resistance and the full charging capacity are also changed depending on an environmental situation or a use status. When the performances of the plurality of secondary cells configuring the assembled battery are largely dispersed, a lifetime of the assembled battery is determined according to the most deteriorated secondary cell.
Under the circumstances, there has been proposed a method in which a rate of the remaining capacity to the full charging capacity in each of the cells during charge and discharge operation is set to be lower as the temperature of the cell is higher during the charge and discharge operation, to thereby keep an even performance (for example, refer to Patent Literature 1).